Metal casing discharge device



METAL CASING DISCHARGE DEVICE Filed June 17, 1942 I INVENTORS ATTGRNEY Patente d May 23, 1944 METAL CASING DISCHARGE DEVICE Donald E. Marshall, Allwood, and William J.

Knochel, Irvington, N. J., assignors to Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., a corporation of Pennsyl- Vania Application June 17, 1942, Serial No. 447,360

6 Claims.

This invention relates to metal casing discharge devices utilizing a pool cathode, and constitutes an improvement over our previously filed application, Ser. No. 360,890, of October 12, 1940, which has become Patent No. 2,308,377.

An object of the present invention is to provide a structure which is simplified and which requires less attention and fewer operations in manufacture.

A further object of the invention is to provide a structure which will enable the level of the pool cathode to be made uniform in all of the manufactured devices and thus enable one device to be substituted for another in the field and operate with substantially the same characteristic.

Yet another object is to obtain a stron bottom wall with minimum material.

A further object of the invention is to economize in the cathode material employed.

In the accompanying drawing, showing essential mechanism embodying the present invention, additional detail structure of which may be seen in the aforementioned application,

Figure 1 is a, view partiall in elevation and partially in vertical section showing a preferred construction of discharge device, and

Figure 2 is a sectional view corresponding to the part shown in section in Figure 1 but in modified form.

In the specific embodiment of the invention disclosed, the feature is shown in connection with a metal casing discharge device generally identified as an ignitron and of the general character shown in the aforementioned application. Such device includes a main casing I0, which may be of cold-rolled steel or other sturd material, having a closed bottom, which in Figure l is shown as a bottom H integral with the side wall of the casing, and shown in Figure 2 as a reentrant header l I inserted in the lower end of the casing and welded vacuum tight therein. This bottom wall in either construction with associated side wall Of the casing forms a container for a, mercury or other liquid cathode pool l2.

Above the pool l2 and also within the casing is an anode l3 spaced from the casing and suitably supported by insulative means. The prior application discusses in detail the support structure for the anode, which in general constitutes a sturdy rod-like conductor hi extending from the anode upwardly through a cylindrical glass seal l5 and secured to a metallic cap it the downwardly directed rim of which is sealed in the end of glass cylinder l5. A suitable lead-in cable I! is connected to the said cap 16.

Likewise, within the casing H] is a starter electrode l8 tapering to provide a downwardly directed tip which dips into the mercury pool cathode. From the upper end of starter electrode l8 extends a supporting rod H) which passes out of the top of the casing through a sealing glass cylinder 20 so as to be supported from a cap 2| the lower rim of which is sealed in the upper edge of said glass cylinder 20. Electrical connection i made with the supportin rod 19 by means of a lead-in wire 22 connected to the said cap 2|.

In the showingof Figure 1, said bottom wall II is preferably provided with a depressed portion or pocket23 underlying the said igniter tip l8. This pocket accordingly gives a maximum depth to the pool cathode in the region of said igniter tip. The discharge from the pool cathode to the anode occurs from surface to surface. In order to start the discharge the igniter tip [8 is employed and apparently operates to best advantage when it is submerged partially in the pool cathode. 'It will accordingly be seen that any material depth for the pool cathode is required only in the region of the starter electrode and that for discharge purposes between cathode and anode the surface area of the cathode assumes the important role. It is to be understood, however, that the invention is not confined to the provision of an extra depth of the cathode, but if desired the starter electrode or igniter may be applied at appropriate depth into a pool cathode carried by a bottom wall which does not 1 have any depression therein. Such modified construction is illustrated in Figure 2.

A feature of the present invention resides in the construction enabling devices to be manufactured uniformly, and this uniformity of manufacture must include uniformit in the depth and surface area of the pool cathode. As shown, the bottom wall H or II is pressed or struck upwardly, forming a frusto-conical mound 24 of no greater size than necessary for its purpose and preferably spaced as far away from the position of the starter electrode as possible. The height of said mound 24 is made to correspond substantially to the depth of mercury required in the container 'for properly forming the pool. The manufacture of the bottom wall, performed by machinery, duplicates the mound as to size and height for all devices made as standard duplicate equipment and consequently by gauging the depth of the mercury pool cathode by the height of the mound, all said devices thus manufactured will have uniform depth of cathode and substantially uniform operating characteristics.

The provision of the struck-up portion or mound 24, has a further and important purpose. Both the fact that it is struck up from the bottom wall and that it tapers inwardly upward lends a very considerable reenforcement to the bottom. It is known that these devices in operation develop high temperatures and that the heat is a direct cause of buckling and other distortion of the envelope, and apparently seriously effective in its deleterious action upon the bottom wall. The bracing obtained b the inwardly tapered mound has been found highly advantageous in obtaining desired rigidity Without undue thickness of wall or necessity of applying separate reenforcement. While bracing effect of a dOWnwardly-struck portion alone, as 23, seems to be of lesser consequence, that bracing also proves of greater effect when employed with a struck-up mound, as 24, in the plate being strengthened.

Th upper plane face of the frusto-conical mound is apertured to receive therethrough a tubulation 25 of appropriate metal. This tubulation is provided with a flange 26 at its upper end, said flange adapted to engage flatwise against the upper face of the frusto-conical mound. The flange and mound are secured together with a vacuum seal as by welding or brazing. The mercury forming the cathode is readily drained through the tubulation until the level of the mercury is substantially the level of the top of the mound. In practice, the thickness of flange 26 is proportionately less than necessary in the showing of the drawing, and therefore, it is proper to refer to the level as substantially the level of the top of the mound although strictlyspeaking the level is actually that of the -top of the flange 26. After the device has been evacuated and the mercury level established the tubulation 25 may be'pinched closed as at ,21. The structure accordingly is such that minimum operations andmaterial are involved for establishing the mercury level and assuring duplication of operating characteristics.

Obviously other detail changes and modifications can be made in the construction of discharge devices without departing from the spirit and scope of the present invention or of the claims appended hereto and all such modifications and changes are intended to be included by the selected disclosures and claims herein.

We claim:

1. A discharge device comprising a sealed metal casing having a bottom for support of a pool cathode, a pool cathode in said casing, and means formed as part of said bottom for limiting the height of said pool cathode.

2. A discharge device comprising a sealed metal casing having a bottom for support of a pool cathode, a pool cathode in said casing, and an open-top mound formed as part of said bottom for establishing the depth of said pool cathode.

3. A discharge device comprising a sealed metal casing having a bottom for support of a pool cathode, a pool cathode in said casing, and an open-top mound formed as part of said bottom for establishing the depth of said pool cathode said mound having a tubulation secured thereto terminating at the top of said mound.

4.. A discharge device comprising a sealed metal casing having a bottom for support of a pool cathode, a pool cathode in said casing, and a mound frusto-conical in shape formed as part of said bottom and having an aperture in its upper face, and a tubulation sealed in said aperture.

5. A discharge device comprising a sealed metal casing having a bottom for support of a pool cathode, a pool cathode in said casing, and a.

mound frusto-conical in shape formed as part of said bottom and having an aperture in its upper face, and a tubulation sealed in said aperture said tubulation having a flange at its upper end overlying the said upper face of the frustoconical mound.

6. A discharge device comprising a sealed metal casing having a bottom wall subject to strains exerted resultant from heat of operation, a pool cathode resting on said wall, and means formed as part of said bottom wall extending out of the plane thereof both inwardly and outwardly of said casing forming a mound and a depression in said wall and reenforcing said wall in opposition to the said strains imposed by heat tending to deform said wall.

DONALD E. MARSHALL. WILLIAM J. KNOCI-IEL. 

